function checkEmail(error_msg) {	
	var email = document.getElementById('tEmail');
	var filter = /^([a-zA-Z0-9_.-])+@(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})+$/;
	if (!filter.test(email.value)) {
		alert(error_msg);
		email.focus
		return false;
	}else{
		return true;
	}
}